The basic objective of this proposal is to construct, computerize and introduce for use in the fields of toxicology, pharmacology and fermentation biochemistry a radiogas chromatograph/mass spectrometer (RGC/MS) in which the MS module is a quadrupole instrument and is coupled in series with the counter unit. A prototype RGC/MS in which the MS module is a sector instrument and is coupled in parallel with the counter already exists in our laboratory. Two biological systems will be used to test the effectiveness of the new RGC/MS unit. The first, chosen for its ease of manipulation, involves an aspect of secondary metabolism in Penicillium patulum. 6-Methylsalicylic acid (6-MSA) and the mycotoxin, patulin, are produced by this organism. The biosynthesis and subsequent catabolism of 6-MSA and patulin will be studied using radiolabelled substrates such as acetate, 6-MSA, m-cresol and patulin. As a model for a drug mode of action study the effect of acetylacetone and dehydroacetic acid on the 6-MSA/patulin pathway will be examined. To test the capability of the upgraded RGC/MS technology in defining states of cell development, an attempt will be made to map the flow of radioactivity from such substrates as glucose, acetate and alanine in the intermediary metabolic network of P. patulum cultures that are producing 6-MSA/patulin and cultures that are not yet so doing. A second demonstration system will be the manner in which 20,25-diazacholesterol (DAC) interferes with cholesterol metabolism in cultured avian muscle cells.